The needle bar of a needle loom must be guided during its movement in the machine stand in a direction perpendicular or essentially perpendicular to the needle-punching support surface. The guide devices provided for this purpose, whether these be rails or rods, lead to problems with heat, lubrication, and sealing. Wear must be avoided as much as possible, because otherwise the punching accuracy during operation suffers. This is disadvantageous especially at high needle-punching densities.
A guide device for the needle bar in a needle loom containing at least one pair of rocker arms, which are arranged on opposite sides of the needle bar, is known from U.S. Pat. No. 4,241,479 A. One end of each of these arms is hinged to the needle bar, while a support device is present on the other end, which supports the rocker arm in question on the machine stand so that it is free to rock. For this purpose, a first bearing surface is formed on the machine stand for each rocker arm; this first bearing surface faces a second bearing surface on the end of the rocker arm. The bearing surface on the machine stand is designed in the manner of an involute gear recess, into which a tooth designed in complementary fashion on the opposite end of the associated rocker arm engages, the tooth thus being free to rock in the gear recess. In this way, the needle bar can be guided along a straight path, wherein the elements participating in its guidance perform exclusively rolling movements.
A needle loom in which the lateral guidance of the needle bar during its up and down stroke is provided by a symmetrically designed four-bar linkage, which is hinged to the needle bar or its carrier and to the machine stand, is known from DE 10 2006 008 485 A1. The dimensions of the four-bar linkage are chosen in such a way that the Ball's point which it forms and which lies on the needle bar describes a straight path within the stroke range of the needle bar.
Although the two previously described designs avoid the sliding type of guides, which are vulnerable to wear, they are relatively complicated mechanically. The two designs contain pivot bearings on the needle bar, which must be lubricated, and the latter design also has an additional number of non-stationary pivot bearings, which increases the difficulty of lubrication even more, because the lubricant must be supplied to these non-stationary pivot bearings continuously for as long as they are in operation.